Estimating cardiorespiratory fitness in heart failure patients with self-reported questionnaires

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiorespiratory fitness (CRF), assessed by peak oxygen uptake (VO2peak), is a powerful predictor of cardiovascular morbidity and mortality. However, performance of a cardiopulmonary exercise test (CPET) is often not feasible or desirable in (older) frail patients, because of physical limitations, transport difficulties, costs and the additional exposure to risks. Other CRF assessment tools, such as questionnaires, are potential alternatives, but have not been validated in frail elderly populations with chronic cardiovascular disease. Purpose The purpose of this study was to investigate the accuracy of two self-reported questionnaires, the FitMáx©-questionnaire and The Fitness Calculator, for assessment of CRF in chronic heart failure (CHF) patients. Methods CHF patients referred for CPET as part of a cardiac rehabilitation programme were eligible for the study. VO2peak was measured with a symptom limited maximal CPET. Participants completed two questionnaires to estimate VO2peak: the FitMáx-questionnaire and The Fitness Calculator. The FitMáx-questionnaire consists of three questions on walking, cycling and climbing stairs [1], and The Fitness Calculator is based on the HUNT3 study [2] and is currently advised by the American heart association as a non-exercise estimate for CRF [3]. Results 29 CHF patients (21 men, 64.2 years ± 12.0) were included with mean VO2peak of 15.7 ± 4.2 mL/kg/min at CPET. Correlation analysis indicated a moderate association between VO2peak assessed by the FitMáx-questionnaire and measured by CPET (r = 0.52) with a mean bias of 1.7 mL/kg/min (95% CI -6.0 – 9.4, p = 0.03). No association was found between VO2peak assessed by CPET and The Fitness Calculator (r = 0.24), mean bias 14.6 mL/kg/min (95% CI -0.5 – 29.7, p <.01). Conclusion The FitMáx©-questionnaire is a moderately accurate tool for estimating CRF in the CHF population. For use in individual patients, efforts should be made to improve the accuracy in this specific patient group. To establish its clinical utility, additional research is needed to evaluate its reproducibility and sensitivity to detect interventional changes in this population.